The IMRT-HIT-SNT trial is a prospective, mono-centric, phase II trial evaluating toxicity in the combined treatment with intensity-modulated radiation therapy (IMRT) and carbon ion (C12) boost in 36 patients with histologically proven (≥R1-resected or inoperable) adeno-/ or squamous cell carcinoma of the nasal cavity or paransal sinuses. Patients receive 24 GyE carbon ions (8 fractions) and IMRT (2.0 Gy/ fraction).